Texas Ebony Foliage

Had this Texas Ebony for about 8 months. All has been fine. Now that it is getting hot here in the desert, all the sudden there are yellowing leaves. I have been watering the same as it needs.
What is strange that will the yellowing leaves, there is also a ton of new leaves and growth.
So not really sure what is going on. The heat has been in the mid 90s with a UV of 8-9, so I out a 50% shade on. It still gets direct sun for a few hours in the early morning.
I was thinking that maybe the older leaves that emerged when it was back east at the nursery are not use to the sun here and that is why they are yellowing. I was told it might need more Nitrogen. So, I am upping that a little.
Any ideas? Or I am worrying about just a natural growth of the tree. Thanks